There's this idea that occurred to me a few days ago, that I've been wondering about ever since.
I'll start by talking about sunglasses. In their simplest form, sunglasses are merely darkened lenses that reduce the amount of light entering the wearer's eyes. If there's too much light, such sunglasses can increase the wearer's comfort.
A slightly more advanced approach involves coloring the lenses, on the theory that undesirable light (glare) may be predominently in some color bands, while desirable light may be in others, in order to increase the ratio of desirable light to undeisrable light, and thus improve not only the wearer's comfort, but his ability to see what he needs to, among the glare.
The pinnacle of sunglass technology, of course, is polarization. It turns out that most surface glare is horizontally-polarized, so wearing sunglasses that are polarized to block horizontally-polarized light, while freely admitting vertically polarized light, offers the greatest ability for the wearer to see what he needs/wants to see, while blocking the most glare.
I was recently thinking about night driving. At night, the primary source of light by which you see is your own car's headlights. The primary source of undesirable glare is direct light from other cars' headlights.
I was wondering; what if car headlights had polarizing filters over them that admitted only horizontally-polarized light, while drivers wore standard vertically-polarized sunglasses? Direct light from oncoming cars' headlights would be blocked from entering one's eyes, but reflected light from your own headlights would be scattered and depolarized, as it bounces off of the things that you need to see, so your own ability to see what you need to see would not be nearly so impaired. (i've just performed an experiment invoving a polarizing filter over a flashlight, while wearing polarized sunglasses. As I expected, polarized light from the flashlight was, in fact, mostly depolarized as it was reflected off of various objects.)
The obvious down side of this is that wearing sunglasses at night would reduce the amount even of desirable light entering your eyes. It seems to me that making the polarized headlights brighter could compensate for this, and that in any event, that the advantage of not being blinded by oncoming headlights might be greater than the disadvantage of having even desired light reduced.
What does everyone think of this idea? Good idea? Bad idea?
I guess putting it into effect would be the difficult part. Assuming it doesn't run afoul of any vehicle regulations, anyone could put polarizing filters over their headlights, and wear polarized sunglasses while driving at night, but this wouldn't really help unless everyone was doing it. Obviously, headlights would need brighter bulbs to begin with, so that the light remaining after the polarizing filter would be in the same amount as normal unpolarized lights. You'd probably want them even brighter still, to compensate for the losses in drivers' polarized glasses, but you wouldn't want to make that adjustment until it could safely be assumed that most drivers were wearing such glasses.
